The invention generally relates to a fan module for moving air through heat exchangers and more particularly to a fan module having features that permit for an even distribution of airflow from a rectangular heat exchanger to a round fan of the fan module and to another rectangular heat exchanger.
Fan modules function to move air through heat exchangers. The heat exchangers are usually grouped together and the fan module is placed upstream (pusher module) or downstream (puller module) the heat exchanger grouping. Typically the heat exchangers are rectangular and the fan orifice is round. Given sufficient distance between the heat exchangers and the fan module the steamlines of air have room to adapt from the one shape to the other. The adapting of streamlines allows an even distribution of air through both the heat exchangers and fan orifice. The heat exchanger aerodynamic losses are minimized by an even flow distribution. The fan performance, aerodynamic and acoustic, is optimized when the airflow is axisymmetric. As used herein, axisymmetric is defined as even distribution of airflow around the fan.
A puller module requires less distance to maintain an even flow distribution. Thus, the use of puller modules is popular since vehicle geometry has changed to require less distance between the fan module and the heat exchangers. Conversely, thermodynamic considerations teach that it requires less work to pressurize low temperature air, which encourages the use of pusher modules. Neither the pusher or puller modules have enough axial distance to ensure an ideal even flow through the heat exchangers. Thus, there is a need to improve the airflow through the heat exchanger for both the pusher and puller module for use in the tight confines of todays vehicle engine compartments.
Conventionally, the shroud portion of the fan module is aerodynamically designed in the area of the support structure of the motor mount ring (stators). The design of the shroud has received little attention. As the gap between the shroud and radiator becomes smaller, the corners of the heat exchanger and the portion behind the hub receive little airfow. The effect of the shroud imposed an aerodynamic loss, by increasing the heat exchanger loss, of a magnitude between the same order and one order less, as the heat exchangers alone. Hence, there is also a need to reduce the aerodynamic losses in the corners of the heat exchangers and reduce the losses at the hub.
An object of the invention is to fulfill the needs referred to above. In accordance with the principles of the present invention, this objective is achieved by providing a fan shroud structure including a shroud body having a pair of opposing first sides and a pair opposing second sides. The first sides are joined with the second sides at corners so as to form a box-like configuration defining an interior space. The shroud body has a front end constructed and arranged to be disposed adjacent to a condenser and a back end constructed and arranged to be disposed adjacent to a radiator. Generally annular wall structure is within the interior space and is constructed and arranged to receive blades of a fan within bounds thereof. Vortex preventing structure is provided in each corner near the back end. The vortex preventing structure is constructed and arranged to prevent large scale eddy current generation of air in the corners as air enters the radiator. Air deflecting structure is provided in each corner near the front end. The air deflecting structure is constructed and arranged to deflect incoming air towards the sides, thereby improving air distribution into the fan.
In accordance with another aspect of the invention a shroud structure includes a shroud body and motor mount structure coupled to the shroud body. The motor mount structure is constructed and arranged to mount a fan motor thereto and to permit axial flow of air through the motor mount structure to cool the motor. The motor mount structure has surfaces defining a diffuser to convert air entering the motor mount structure at velocity pressure to static pressure as the air exits the motor mount structure.
In accordance with yet another aspect of the invention, a fan module, constructed and arranged to be mounted between a condenser and a radiator, includes a shroud structure and a motor mount structure coupled to the shroud structure. The motor mount structure is constructed and arranged to permit axial flow of air through therethrough. A fan motor is carried by the motor mount structure. A fan hub is driven by the motor for rotation within the shroud structure. The fan hub carries a plurality of fan blades extending radially therefrom to define an axial flow fan. The fan hub including a plurality of hub blades defining a mixed flow impeller. The axial flow fan and the impeller sharing a common axis of rotation thereby defining nested fans to increase the net airflow through the fan module.
Other objects, features and characteristics of the present invention, as well as the methods of operation and the functions of the related elements of the structure, the combination of parts and economics of manufacture will become more apparent upon consideration of the following detailed description and appended claims with reference to the accompanying drawings, all of which form a part of this specification.